For any laser cutting operation, the blank being cut must be initially pierced therethrough before the actual cutting operation can begin. This initial piercing or penetration through the blank is known in the industry as "peck through," which is a machining term stemming from a peck drilling operation wherein the drill is retracted periodically to remove metal chips. Laser cutting is similar in that it is oftentimes necessary to pulse the laser on thick materials to prevent a pool of molten material from forming. As is well known, the penetration or peck through operation performed by lasers can be a time consuming process.
It will be understood that it is necessary to penetrate through the blank before actual cutting of a workpiece therefrom can begin. In the prior art, the penetration process for laser cutting typically involves the use of a time delay having a predetermined penetration time. The penetration time of necessity must be determined experimentally for each material and thickness, which adds to the overall time needed for the process. Moreover, a safety factor is generally built into such Predetermined penetration times to account for "hard spots" in the material or to otherwise ensure penetration of the blank. As a consequence, the predetermined penetration time has traditionally been twice the time required as found through testing. Clearly, the additional time allocated for penetration of the material, as well as the initial testing required, reduces the productivity and efficiency of the laser cutting process. This is particularly true since several workpieces are cut from a blank and multiple cuts for a single workpiece are oftentimes required.